Diversified healthcare products company Covidien Ltd. issued a voluntary recall of its prefilled syringes containing heparin because some might contain a contaminant. Mansfield-based Covidien said its supplier, Wisconsin-based Scientific Protein Laboratories, said two lots of Heparin Sodium USP active pharmaceutical ingredient it received might contain a heparin-like contaminant. Covidien said it is recalling the product as a precaution; no adverse events have been reported. Last week, Scientific Protein said an ingredient it provided contained oversulfated chondroitin sulfate, a chemical that does not occur naturally.